1. Field of the Invention
The present invention relates to a semiconductor device and a method of fabricating the same, and more particularly, to a layout of an outermost cell region of a semiconductor device and a method of forming a contact pad using the same.
2. Description of the Related Art
With the development of highly integrated semiconductor devices in recent years, the size of a pattern in a cell region of the device has been reduced. Various resolving power technology such as a phase shift method or modified illumination method is employed in order to form a fine pattern. However, a pattern may be transferred at the outermost portion of a cell region with an undesirable result due to optical diffraction or interference.
FIG. 1 is a plan view illustrating a conventional layout including a cell region.
Referring to FIG. 1, a cell region “a” includes an active region defined by an isolation layer 10. An outermost portion of the cell region a is divided into a first outermost portion “c” and a second outermost portion “b”. The first outermost portion c is disposed in parallel with a sense amplifier 22 spaced from the first outermost portion c by a predetermined distance. The second outermost portion b is disposed in parallel with a word line drive portion 20 spaced from the second outermost portion b by a predetermined distance. A corner of the cell region a is included in the first outermost portion c.
The first outermost portion c includes a first active region 14 having the same shape as that of an inner active region 12 disposed inwardly from the first outermost portion. Further, the first outermost portion c includes at least two second active regions 16a, 16b spaced from the first active region 14 and adjacent thereto by a predetermined distance, and having respective shapes different from that of the inner active region 12 disposed inwardly from the first outermost portion c.
An active region disposed at the outermost portion of the cell region a, specifically, an active region formed at the first outermost portion c, has an incomplete shape, as if the inner active region 12 is formed incompletely. Because of that, since the size of the second active regions 16a, 16b is smaller than that of the inner active region 12, the second active regions 16a, 16b on the mask cannot be transferred on the substrate appropriately. Furthermore, a lifting phenomenon may occur, in which the second active region patterned on the mask is not transferred on the substrate. The lifting phenomenon may also occur in the second outermost portion b.
FIG. 2 is a plan view illustrating a conventional method of forming a contact pad in a cell region.
Referring to FIG. 2, a gate line 30 extends to form an acute angle with the longitudinal direction of the inner active region 12. A bit line 36 meets the gate line 30 vertically, and contacts and passes a bit line contact pad 34. A lower electrode contact pad 32 is formed on the active region between the gate lines 30. However, there may occur a problem in which a contact pad to connect the bit line on the second active regions 16a, 16b, or a capacitor lower electrode is not formed well.